A microscope is a scientific instrument that is used for the visualization of objects, which can be either small cells or have details that are too small to be resolved by the naked eye.
There are many types of microscopes available on the market. The most common of these and the first to be invented is the so-called optical microscope, which uses light in a system of lenses to magnify images of the samples. The image from the optical microscope can be either viewed through an eyepiece or, more commonly nowadays, captured by a light-sensitive camera sensor to generate a so-called micrograph. There are a wide range of sensors available to catch the images. Non-limiting examples are charge-coupled devices (CCD) and scientific complementary metal-oxide semiconductor (sCMOS) based technologies, which are widely used. These sensors allow the capture and storage of digital images to the computer. Typically there is a subsequent processing of these images in the computer to obtain the desired information.
The illumination sources as used in optical microscopes have been developed over the years and wide varieties of illumination sources are currently available, which can emit light or other type of radiation at different wavelengths. Optical filters can be placed between the illumination source and the sample to be imaged in order to restrict the wavelength of the radiation illuminating the sample.
Modern biological microscopy uses fluorescent probes for imaging specific structures within a cell as the sample. In contrast to normal trans-illuminated light microscopy, the sample in fluorescent microscopy is illuminated through one or more objective lenses with a narrow set of light wavelengths. These narrow set of light wavelengths interact with fluorophores in the sample, which then emit light of a different wavelength. This emitted fluorescent light is detected in a detector and is used to construct the image of the sample.
The use of multiple images enables a 3-dimensional reconstruction of the sample to be made. This 3-D reconstruction can be done by generating images at different positions on the sample, as the sample moves relatively to one or more objective lens. Depending on the number of detection units necessary, several detectors may be required. These detectors are quite expensive and a microscope designer will wish to reduce the number of detectors. The use of a single detector, which is moved during the imaging process, can be disadvantageous in that the movement of the detector itself can slightly effect the position of the sample, due to vibrations. Alternately the sample itself may move for other reasons whilst the detector is being placed into another position. This movement of the detector requires a precise and fast movement of a part of hardware, which is comparatively massive and in turn leads to further increase in development costs and/or in extra parts of equipment.
A number of papers and patents have been published on various aspects of microscopy. For example, European patent EP 1 019 769 (Carl Zeiss, Jena) teaches a compact confocal feature microscope, which can be used as a microscope with a single objective lens or with multiple objective lenses. The microscope has separate directions of illumination and detection. The direction of detection in the objective lens is aligned inclined at a set angle in relation to the direction of illumination.
Another example of a microscope is taught in the paper by Krzic al. “Multi View Light-Sheet Microscope for Rapid in tow Imaging”, Nature Methods, July 2012, vol. 9 No. 7, pages 730-733. This paper teaches a multi-view selective-plane illumination microscope comprising two detection and illumination objective lenses. The microscope allows in tow fluorescence imaging of the samples with subcellular solution. The fixed geometrical arrangement of the imaging branches enables multi-view data fusion in real time.
Document DE 195 09 885 A1 discloses a stereo endoscope wherein illuminating light is transmitted by the light guide inserted through the elongate inserted section and is projected out of the distal end surface of the inserted section. The illuminated objects pass through the respective pupils of the two objective lens systems arranged in parallel within the distal end section of the inserted section and their images are formed on the focal surface. The respective images are transmitted to the rear side by one common relay lens system. The transmitted final images are formed respectively on the image taking surfaces of the image taking devices. The respective images are photoelectrically converted by the respective image taking devices and further processed to be signals, are displayed in the monitor and are stereo-inspected through shutter spectacles.
Document U.S. Pat. No. 4,440,475 A discloses a device having a electromagnetic lens for focusing the analyzing electron beam that is provided with a central channel along the axis of the electron beam which is intended to pass through a mirror-objective having high magnification. The electromagnetic lens further comprises a lateral channel in which it is placed an auxiliary objective having low magnification. An optical illumination system, the axis of which is contained in the plane of the axes of the objectives, illuminates the sample either through the principal objective or through the auxiliary objective. An orientable mirror which is orthogonal to the plane aforesaid and placed at the intersection of the beams which form the images through the two objectives permits the use of the same observation means both for low magnification and for high magnification.
In document U.S. Pat. No. 5,132,837 A is an operation microscope disclosed including a plurality of objective lenses arranged at different angles with respect to an object to be viewed and a selecting optical system having a function of selecting one of light beams from the objective lenses and enabling the object to be observed at the different angles. Accordingly, a visual field for observation of an object to be operated may be expanded.
Document US 2012/044486 A1 discloses a system and a method for detecting defects on a waver.
Document WO 2008/028045 A2 discloses a system and method for robust finger-print acquisition comprising combined multispectral and total-internal-reflectance biometric imaging systems. A platen has multiple facets, at least one of which has a surface adapted for placement of a purported skin site by an individual and another facet may include an optical absorber. An illumination source and an optical arrangement are disposed to illuminate the purported skin site with light from the illumination source along distinct illumination paths, including paths at angles less than the critical angle and paths at angles greater than the critical angle. Both multispectral and total-internal-reflectance illumination are received by an imaging system. The imaging system may include first and second imaging locations adapted to record images from separate illumination paths. The platen may also include non parallel exits facets